I use two sizes and love them. I use commercial seed starting mix in mine though. I think Diane also bought soil molds a couple of years ago. I plant tomato and pepper seeds in a 3/4 inch block which later slides into a 2 inch block. If the weather isn't ready when it outgrows those then I pot them into 6 inch pots until they can be planted in the garden. Using the small block saves a lot of space on the seedling shelves while they need to be warm and under lights.

How do you keep them from falling apart? I use paper cups and sometimes they disintegrate before they go in the groubd?

I use a really wet mix and press it hard into the blocks. Once they germinate the roots also help to hold it together. I really don't have much trouble with them, but there is a learning curve.

Thanks! I've considered them before. Maybe next year. I like the idea of little ones to start!